Static Assignment

The Demonstration Scenario defines a structure SWAP_Order that must be handed over to each service to be executed. Here, no additional structure is required, since the assignment strategy of the execution engine completely relies on its default behavior, where the resource, which has the lowest number of queue elements, is always selected for the service execution. However, the default assignment requires at least a global defined Device Registry.

PFDL Definition

Struct SWAP_Order
    order_id:number
    stand:Stand_Segment
    segments: Light_Segment[]
    number_light_segments: number
End

Struct Stand_Segment
        stand_shape:string
        stand_height:number
        stand_id:string
End

Struct Light_Segment
        color: string
        diameter: number
        segment_id:string
End

Struct ResourceAssignment
    job_resource:string
End

#production Task the defines the overall process
Task productionTask
        #define a single service GetPartsFromWarehouse
   GetPartsFromWarehouse
            In
                SWAP_Order
                {
                    "order_id":1000,
                    "stand":{
                          "stand_shape":"plate",
                          "stand_height":3,
                          "stand_id": "Default"
                    },
                    "segments":
                    [
                    {
                          "color": "red",
                          "diameter": 5,
                          "segment_id": "Default"
                    },
                    {
                          "color": "green",
                          "diameter": 5,
                          "segment_id": "Default"
                    }
                    ],
                          "number_light_segments": 1
                }
                ResourceAssignment
                {
                    "job_resource":"opc.tcp://localhost:4080"
                }

            Out
                order:SWAP_Order
End

Process Execution

To execute the above-defined PFDL-process, a small python script is required to set up the execution engine and the docker environment:

import time, os, sys
#add directories to the system path
sys.path.append(os.path.join(os.path.dirname(__file__), "../."))
sys.path.append(os.path.join(os.path.dirname(__file__), "../tests/test_helpers/."))
#import the main function
from main import main
#import the docker environment
from util.start_docker_compose import DockerComposeEnvironment

if __name__ == '__main__':
    #configure the required docker environment
    env = DockerComposeEnvironment(["Service_Server", "Dashboard"])
    #start the docker environment
    env.run_docker_compose("./Tutorial/docker-compose.yaml")
    #wait until the server started
    time.sleep(10)
    #run the execution engine
    main()
    #shut down the docker environment
    env.stop_docker_compose()

Here, we first need to add the root directory of the repository to the system path to import the main function of the execution engine. Beside, we can re-use the docker-environment from the test section.

The process can then be executed from the command line with:

python Tutorial/static_assignment.py "opc.tcp://localhost:4840" "Tutorial/PFDL/static_assignment.pfdl" "dashboard_host_address"="http://localhost:8080"

so that we can execute the process and map it on the SWAP-IT Dashboard. In case that the log messages of the execution engine should be captured, the command line argument can be simply adjusted to:

python Tutorial/static_assignment.py "opc.tcp://localhost:4840" "Tutorial/PFDL/static_assignment.pfdl" "dashboard_host_address"="http://localhost:8080" "log_info"=True